|
Abstract:
|
The goal of the present work is to improve shale reservoir stimulation treatment by using ultra light weight proppants in fracturing fluids . Slickwater has become the most popular fracturing fluid for fracturing shales in recent times because it creates long and skinny fractures and it is relatively cheap . The problem with slickwater is the high rate of settling of common proppants , e .g . sand , which results in propped fractures which are much smaller than the original fractures . Use of gels can help in proppant transport but introduce large formation damage by blocking pores in nano -darcy shales . Gel trapping in the proppant pack causes reduction in permeability of the proppant pack . The light weight proppants which can easily be transported by slickwater and at the same time be able to provide enough fracture conductivity may solve this problem . Three ultra light weight proppants (ULW1 , ULW2 , and ULW3 ) have been studied . The mechanical properties of the proppant packs as well as single proppants have been measured . Conductivity of proppant packs has been determined as a function of proppant concentration and confining stress at an average Barnett shale temperature of 95oC . The crush strengths of all the three proppant packs are higher than typical stresses encountered (e .g . , Barnett ) . ULW1 and ULW2 are highly deformable and do not produce many fines . ULW3 has a higher Young’s modulus and produces fines . Conventionally , the proppant conductivity decreases with decreasing proppant concentration and increasing confining stress . But in cases of ULWs , for a partial monolayer , conductivity can be as large as that of a thick proppant pack . The settling velocity is the lowest for ULW1 , intermediate for ULW2 and the highest for ULW3 . This work contributes new mechanical , conductivity , and settling data on three ultra light weight proppants . Application of light weight proppants in stimulation treatments in shale reservoirs can lead to large propped fractures , which can improve the productivity of fractured shale reservoirs . |